def solve():
    X = int(input())
    if X >= 30:
        print('Yes')
    else:
        print('No')

if __name__ == '__main__':
    solve() def solve():
    X = int(input())
    if X >= 30:
        print('Yes')
    else:
        print('No') solve X = int(input()) X int(input()) int input() input if X >= 30:
        print('Yes')
    else:
        print('No') X >= 30 X 30 print('Yes') print 'Yes' print('No') print 'No' if __name__ == '__main__':
    solve() __name__ == '__main__' __name__ '__main__' solve() solve def solve():
    X = int(input())
    if X >= 30:
        print('Yes')
    else:
        print('No') def solve():
    X = int(input())
    if X >= 30:
        print('Yes')
    else:
        print('No') solve
def solve():
    X = int(input())
    if X >= 30:
        print('Yes')
    else:
        print('No')

if __name__ == '__main__':
    solve()